Visual Art/Aidan Dunne: The first thing to say about Paul Mosse's mixed-media works in Sandwiched Space is that they are extraordinary objects. He starts out with very precise drawings on paper, patterns for everything that follows.

Reviewed: Paul Mosse: Sandwiched Space, Green on Red Gallery, Dublin, until June 21st (01-6713414) Jack Donovan, Cross Gallery, Dublin, until June 14th (01-4738978) Kimio Tsuchiya: Undeveloped Memory, 5th@Guinness Storehouse, Dublin, until June 22nd (01-4084800)

The first thing to say about Paul Mosse's mixed-media works in Sandwiched Space is that they are extraordinary objects. He starts out with very precise drawings on paper, patterns for everything that follows. These drawings are derived from some original in the past. They may represent something, but it would be rash to hazard a guess as to what that might be. Usually the pattern forms the basis for a network of cuts into plywood sheets, and from there each work takes off in its own direction, typically involving the accretion of various materials: bits of plywood, nails, glue, plastics, paint and more.

Each piece is made according to strict but arbitrary procedures. There is a curious sense of inevitability about the way each one assumes a dense, heaped, congested form, not least because of a circularity in the way everything taken away feeds back into the process. Whatever of the ancestor source drawing back at the beginning of all this, the end products are not representations of anything, but they certainly invite associations with many things, including maps or diagrams, circuit boards, aerial photographs, sections of landscape, scale models and proliferations of organisms of various kinds.

In a wider frame, they evoke relentless, algorithmic processes in nature and culture. In particular, in the natural content, they evoke evolution by natural selection, in the way they emerge as physical forms via the application of rules. For the most part they are not beautiful in the conventional sense, but there is often an incidental beauty along the way, and individual pieces, including Ballinglen III, are indeed beautiful. The major pieces in the show are more fascinating than beautiful, and they really are fascinating. Mounted in big perspex boxes, Slice, Years and Matchsticks are a formidable trio of works.

Their labyrinthine honeycombs of spaces folded endlessly in on themselves, their disconcerting concretions of wood, paint, sawdust and other stuff somehow form worlds in themselves. They have a conceptual richness and cohesiveness, and a strange physical presences, that marks them as perhaps Mosse's finest work to date, and they rank as outstanding in any context.

Although he has exhibited sparingly over the years, the Limerick painter Jack Donovan has long been a distinctively individual presence, and a quietly influential one, in Irish art. This is partly through his time as head of Limerick's art school, particularly in what might be termed the slightly more anarchic days of art education. But his work has also been influential in terms of both its idiosyncrasy and its technical rigour.

If you are seeing it for the first time you may initially doubt the latter, because Donovan uses a very simplified style of representation to create images imbued with self-deprecating humour and, often, skewed eroticism. But if you make only a superficial reading of the content you may miss his fine colour sense, his compositional flair and his judiciously measured use of form and pigment itself.

Throughout his career his iconographic style has been remarkably consistent, so that he has cumulatively created an instantly recognisable imaginative world. His main male protagonist is usually a clown, his setting usually a circus. Life is viewed as a circus or a theatre of cruelty and farce - as in seaside-postcard farce. The clown, variously heroic, pitiful, ridiculous, is a plaything of fate, a slave to desire.

In Donovan's world women are often lasciviously envisaged as sexually seductive and remote, either fleshy and passive, like his plump Suzannah, or fantasy dominatrices, like his Circus Girl with Pony.

As his invocation of Suzannah suggests, the work in the show uses many references to art history and includes a version of Manet's Le Déjeuner Sur L'Herbe. These homages are usually funny in a mildly self-mocking way.

A number of smallish floral still lifes are straightforwardly good, and good- humoured, paintings. But overall there is a dark undercurrent running through Donovan's pictures that in all probability has to do with his mordant awareness of the absurdity of things but also relates to their occasional erotic cruelty. It's striking that his work is as provocative and edgy as ever.

You have to experience Kimio Tsuchiya's installation Undeveloped Memory to get a flavour of it, and you wouldn't want to experience it if you're prone to claustrophobia. It involves hearing a steel door ease closed behind you as you negotiate a narrowing corridor to enter a closed cylindrical steel space, the walls and ceiling of which are lined with 300 ticking clocks, all set to different times. There is a distinctly submarine feeling to the space, and the massed ticking plays odd acoustical tricks.

Tsuchiya uses recycled materials and objects in his work. He is concerned with all the personal histories bound up in the ticking of those clocks, the lives lived with reference to their faces.

Specifically he refers to Japan's economic boom of the late 1980s and early 1990s, the era of the "bubble economy". He sees it as a time when much of the past was swept away in a frenzied and misguided pursuit of consumerist modernity.

So for his huge floor piece Rose Of Ashes he burned what remained of demolished houses and their contents to create a fine ash that becomes an emblematic, perishable sculpture of a blossom.

His much smaller broken glass flowers are equally impressive. It could be argued that the need for an explanatory context limits the work, but that is not quite the effect.

Even without a word of explanation his pieces would still be highly effective, and Undeveloped Memory, particularly, prompts us into a consideration of lives lived, time lost.